Pilot Evaluation of RT-PCR/Electrospray Ionization Mass Spectrometry (PLEX-ID/Flu assay) on Influenza-Positive Specimens

Samuel Cordey*, 1, 2, 3, Yves Thomas 2, 3, 4, Patricia Suter 2, 3, 4, Laurent Kaiser 1, 2, 3, 4
1 Swiss National Reference Centre for Emerging Viral Diseases, University of Geneva Hospitals, Geneva, Switzerland
2 Laboratory of Virology, University of Geneva Hospitals, Geneva, Switzerland
3 University of Geneva Medical School, Geneva, Switzerland
4 Swiss National Reference Centre for Influenza, University of Geneva Hospitals, Geneva, Switzerland

© Cordey et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 4 Rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland; Tel: ++41 22 3724079; Fax: ++41 22 3724097; E-mail:


The PLEX-ID/Flu assay has been recently developed to enable the detection and typing of influenza viruses based on the RT-PCR/electrospray ionization mass spectrometry technology.

This novel assay was evaluated for typing performance on 201 positive influenza A or B nasopharyngeal swab specimens (NPS) detected by real-time RT-PCR during the 2010-2011 season. The PLEX-ID/Flu assay detected and characterized 91.3% and 95.3% of all influenza A and B samples, respectively. All non-typeable influenza A and B specimens by the assay showed low viral loads with threshold cycle values ≥ 33. Taken together, and although our results need to be confirmed by further prospective studies, the PLEX-ID/Flu assay detected positively and gave a typing result for 93% of all NPS detected positively by real-time RT-PCR, thus suggesting a potential role for influenza virus surveillance among other techniques.

Keywords: Influenza surveillance, influenza typing, PLEX-ID/Flu assay..